Laserfiche WebLink
( CAA <br /> Cross Sections <br /> Two generalized cross sections were prepared for this SCM The location of the cross section <br /> lines is shown on Figure 2 The cross section lines were chosen to include the most borings and <br /> wells, to be somewhat perpendicular to each other, and to run through the suspected source area <br /> Cross section A-A' is shown on Figure 6 and cross section B-B' is shown on Figure 7 Soil type <br /> information was taken from well lags, boring logs, and cone penetration testing(CPT) logs The <br /> soil types were grouped into coarse-grained sediments (sands and gravels), fine-grained <br /> sediments (silts and clays), and stiff fine-grained (which is a CPT logging designation that does <br /> not translate into a Unified Soil Classification System soil type) The vertical extent of TPHg <br /> and benzene are plotted on these cross sections based on the aerial extent of these compounds <br /> shown on Figure 3 Copies of the well logs, boring logs, and CPT logs are presented in <br /> Appendix B A summary of the soil boring details and the well construction details is presented <br /> as Table 6 <br /> Graphs <br /> ® Cambria plotted concentration versus time for TPHg and benzene in well S-1 These graphs are <br /> presented as Figures S and 9 Groundwater elevation was also plotted with each compound A <br /> trendline was added to the graph to demonstrate the overall concentration trend Both TPHg and <br /> benzene show a decreasing trend <br /> Contaminant Mass Estimates <br /> The TPHg and benzene mass in groundwater were estimated by correlating an estimated average <br /> hydrocarbon concentration with a specific volume of impacted groundwater The remaining <br /> TPHg and benzene mass in groundwater was calculated using the following equation <br /> Hydrocarbon Mass (pounds) = Aquifer Volume (gallons) x Porosity (%) x Avg Concentration (micrograms/liter) x 109 <br /> (kilograms/microgram)x 3 785(Liters/gallon)x 2 205(pounds/lalogmm) <br /> The methods for estimating the TPHg and benzene concentration and groundwater volume are <br /> described below <br /> TPHg and benzene have been detected in groundwater primarily in the vicinity of the <br /> northwestern dispenser Figures 4 and 5 depict the estimated aerial extent of TPHg and benzene <br /> in groundwater based on the May 2003 groundwater sampling data <br /> 0797 3 <br />